"setup_develop" was still being called for swift3, even if it's
not in enabled services. This wraps that call in an
"is_service_enbled" conditional so that stack.sh doesn't attempt
to set it up if it's not enabled.
- Fixes bug 1021150.
Change-Id: I26ed1a1e73eee24da78580eda3b13e5d3eb65361